Most of us loved it when Jimmy Carter repudiated the Imperial Presidency by walking down Pennsylvania Avenue after his inauguration four years ago. Very few noticed that in moving to fight unemployment, the new president also put in for a heavy dose of inflation.

Most of us also loved it when Ronald Reagan repudiated the Peanut Presidency by what was called the "elegance" of his inauguration. Very few noticed that in declaring war on inflation, the new president may have thrown away the crucial weapons.

The war on inflation was declared in the most unambiguous terms. After six paragraphs of obligatory grace notes, President Reagan turned in his inaugural address to the "business of our nation." The next 18 paragraphs, the whole first part of the speech, dealth with "an economic afflictin of great proportions . . . the longest and one of the worst sustained inflations in our national history."

Small-town morality provided the model for the analysis that followed. There were good guys -- "professionals, industrialists, shopkeepers, clerks, cabbies and truck drivers." There was also a bad guy. "In this present crisis," Reagan said, "government is not part of the solution; it is the problem."

The prescription for arresting inflation favored by the Reagan administration follows closely on that model. As a prime step, dollars will be returned from the villain to the good guys. There will be proposed a massive tax cut, 10 percent annually in three installments, working chiefly to benefit individuals.

Government will be made to pay for the tax cut, by relentless chopping of non-defense spending. In that spirit, the new budget director, David Stockman, spoke of "major surgery" on domestic programs.

The theory behind that approach is the theory of inflationary expectations.

he idea is that a dramatic tax cut accompanied by drastic reductions in spending will break the psychology of inflation that has gripped the private sector. Market and corporations will steady themselves and begin to invest with confidence. Output per worker, or productivity, will rise, and goods in short supply will become abundant. Inflation rates will then head down.

Since expectations are a matter of guesswork, nobody can consummately challenge that theory. Surely it deserves a chance. If it works, all of us will be healthier and wealthier. Many of us will be wiser.

For there are reasons to think the theory might not prove practical. It is still not clear that the Reagan administration will have the stomach for the truly deep expenditure cuts required to offset the huge tax reductions now in prospect. Even Stockman, who talks of "blood on the floor," only mentions such fringe items in the spending picture as student loans, unemployment benefits, public jobs and investments in synthetic fuels, highways and irrigation. The Congress will surely not cut deeper.

Even if huge expenditure cuts are made, moreover, other forces besides government contribute to inflation. There is the cartel of the oil-producing countries known as OPEC. It has doubled energy prices in the past 18 months. With the Iran-Iraq war still on, there is the prospect of more shortages and another push in prices beginning this spring.

Then there are the big unions and the big companies. With inflation now rising at a rate of about 10 percent annually, union leaders are under heavy pressure to go for wage increases to keep pace. Big companies are in the habit of paying up and passing the increase on to consumers in the form of higher prices. Thus there is a deep connection between the momentum of inflation and the wage-price cycle.

The weapons for dealing with OPEC and with the big unions and companies all lie within the province of government. But President Reagan seems, almost without knowing it, to have put them aside. He has foresworn government actions that woud restrain wages and prices. He has no energy program to restrain the puch of OPEC.

Instead of early success, accordingly, Reagan may face an early emergency. He may find oil prices going up, followed by rising wages and higher prices. Interest rates would then be kept high by this Federal Reserve. The high rates would dampen economic activity. With unemployment rising, the Congress would be extremely loath to cut social benefits. Inflation would take off once again.

Nobody can say what the Reagan administration would do then. But the Carter experience provides a warning. The early applause so dazzled the last president that he proved unable to adjust when inflation emerged as Public Enemy No. 1.

If there really is a new beginning, not just the same old new beginning, then Reagan will have learned the lesson of Carter's failure. He will be able, if matters go awry, to overcome ideology and accept the premise that, when it comes to checking OPEC and big unions and big companies, a certain, not unuseful role can be played by government.